Hospitals in the U.S. have long been able to obtain exemption from federal income tax because they meet the requirement known as the standard of “community benefit.” Yet lawmakers and scholars know virtually nothing about the actual workings of tax-exempt hospitals, or about whether, how, and to what extent they deliver benefits to their communities. Within the last five years, however, IRS tax return forms have started asking hospitals to quantify these benefits, as well as to give detailed information about their financial practices with respect to their patients. These new questions coincide with new requirements for tax-exempt hospitals put in place as part of 2010’s health care reform bill, the Affordable Care Act. The new tax return data offers a first-time opportunity to evaluate the workings of tax-exempt hospitals from the perspective of both the traditional requirements for tax-exempt hospitals and the 2010 reforms of the Affordable Care Act. This Article analyzes data from all tax-exempt hospitals in the U.S. in 2012 to show that tax-exempt hospitals differ widely in their provision of community benefits (and financial practices). In particular, these activities vary systematically in relation to their different notions of “community” and the characteristics of the communities where the hospitals are located. This evidence demonstrates that tax-exempt hospitals seem to be responding to the specific needs of their own communities when allocating their resources among different community-benefit activities. The data show, in addition, that while tax-exempt hospitals are generally adopting the financial policies that Congress and the IRS are requesting, hospital financial aid policies also vary by community. These findings raise several fundamental questions for lawmakers and tax policy scholars in the era of the Affordable Care Act. In particular, the findings suggest that lawmakers need to grapple seriously with how they allow tax-exempt hospitals to define their communities. For example: is it appropriate for tax-exempt hospitals merely to benefit a narrowly defined community or should they operate in terms of a broader understanding of community? In light of the new data presented, this Article considers these questions and outlines several alternatives to the “community benefit” standard to address them.